CROSS REFERENCE TO RELATED APPLICATION
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The present invention relates generally to internal combustion engines having at
least one reciprocating piston within a cylinder, and more particularly to seals between
the reciprocating piston and a cylinder wall.
2. Related Art
[0003] Typical internal combustion engines are provided with at least one piston body which
reciprocates within a cylinder of an engine block. In general, each piston body includes
a plurality of ring grooves, each of which receives and operably supports a piston
ring. In operation, the piston rings remain in the ring grooves and travel with their
respective piston bodies in a reciprocating motion within cylinders of an engine block.
Among other things, the pistons rings function to seal combustion gasses in a combustion
chamber above the piston body, to transfer heat from the piston body to the cylinder
wall, to restrict the passage of oil from the crank case to the combustion chamber
and to provide a generally uniform oil film on the cylinder wall. Such piston rings
are typically biased with a spring force in a radially outward direction against the
cylinder wall to establish the seal between the piston body and the cylinder wall.
(see
FR-A-2030083)
SUMMARY OF THE INVENTION
[0004] One aspect of the present invention provides for a piston ring for sealing a cylinder
wall to a piston body. The piston ring includes a ring body that extends about an
axis and has an inner face and an outer face. The inner face presents at least two
ridges that extend in a radially inward direction. The ridges on the inner face are
spaced from one another, and the outer face presents a groove. A spring of an elastomeric
material substantially circumferentially surrounds the ring body and is seated in
the groove on the inner face. The spring biases the ring body in the radially inward
direction to seal the ridges on the inner face against the piston body. The ring body
also has at least one oil drainage port which extends at an angle relative to the
radially inward direction from the inner face to a location on the outer face on one
axial side of the spring for conveying oil out of a space between the ridges.
[0005] The piston ring may be seated in a channel of a cylinder wall and sealed against
the skirt of the piston body. As such, the piston ring remains generally stationary
and does not move relative to the cylinder wall during operation of the engine. This
location allows for increased stability of the piston body as it reciprocates in the
cylinder of the engine without compromising the length of the skirt, i.e. the skirt
may extend downwardly past the cylinder wall when the piston body is in a bottom dead
center position. The piston ring is also resistant to blow by. Because the oil drainage
ports extend at an angle relative to the radially inward direction, they do not interfere
with the inner-most surfaces of the ridges and thus do not compromise the oil and
gas seal between the cylinder wall and the piston body provided by the piston ring.
Additionally, the oil drainage ports do not compromise the structural integrity of
the ring body.
[0006] Another aspect of the present invention provides for a power cylinder assembly. The
power cylinder assembly includes a cylinder wall with a substantially circumferentially
channel formed therein. The power cylinder assembly also includes a piston body with
a skirt, and at least a portion of an outer surface of the skirt extends substantially
continuously around a circumference. The power cylinder assembly further includes
a piston ring which is seated in the channel of the cylinder wall and has a ring body
that extends about an axis. The ring body has an inner face with at least two ridges
that extend in a radially inward direction and are spaced from one another in an axial
direction. The ring body also has an outer surface that faces opposite of the inner
surface and presents a groove. The piston ring further includes a spring of an elastomeric
material substantially circumferentially surrounds the ring body and is seated in
the groove on the outer face. The spring biases the ring body in the radially inward
direction to seal the ridges against the circumferentially continuous portion of the
skirt of the piston body. The ring body has at least one oil drainage port which extends
at an angle relative to the radially inward direction from the inner face to the outer
face on one axial side of the spring for conveying oil out of a space between the
ridges.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] These and other features and advantages of the present invention will be readily
appreciated, as the same becomes better understood by reference to the following detailed
description when considered in connection with the accompanying drawings wherein:
Figure 1 is a perspective and elevation view of an exemplary embodiment of a piston
ring;
Figure 2 is a sectional view of an exemplary embodiment of a power cylinder assembly
and including the piston ring of Figure 1 and showing a piston body in a top dead
center position;
Figure 3 is another sectional view of the exemplary embodiment of the power cylinder
assembly with the piston ring of Figure 1 and showing the piston body in a bottom
dead center position;
Figure 4 is a cross-sectional and fragmentary view showing the piston ring of Figure
1 disposed within a channel of a cylinder wall and in sealing engagement with a piston
body;
Figure 5 is a cross-sectional and enlarged view showing a portion of the piston ring
of Figure 1;
Figure 6 is a front elevation view of a ring body of the piston ring of Figure 1;
and
Figure 7 is a top elevation view of the ring body of the piston ring of Figure 1.
DESCRIPTION OF THE ENABLING EMBODIMENT
[0008] Referring to the Figures, wherein like numerals indicate corresponding parts throughout
the several views, an exemplary embodiment of a piston ring
20 for sealing a piston body
22 to a cylinder wall
24 of a power cylinder assembly
26 of an internal combustion engine is generally shown in Figure 1. Referring now to
the cross-sectional views of Figures 2 and 3, the exemplary piston ring
20 is shown as installed in a power cylinder assembly
26 of an internal combustion engine having an engine block
28 and a two-piece cylinder liner
30 which together present an axially extending cylinder wall
24 having a channel
32 that extends substantially circumferentially around the cylinder wall
24. Specifically, in the exemplary embodiment, the piston ring
20 is disposed between ends of the cylinder liner
30 pieces which are spaced axially from one another to present the aforementioned channel
32. However, it should be appreciated that the channel
32 could be formed into the cylinder wall
24 through a range of different manners. For example, the channel
32 could be formed directly into the engine block
28 without any cylinder liner
30. The exemplary piston ring
20 is shown installed in a diesel fueled compression ignition engine; however, it should
be appreciated that the piston ring
20 could alternately be used in a range of different types of internal combustion engines
including, for example, spark ignition engines or horizontally opposed two piston
per cylinder engines.
[0009] Referring still to Figures 2 and 3, the piston body
22 of the exemplary power cylinder assembly
26 includes one or more upper piston rings
34 (a plurality being illustrated in the exemplary embodiment) which are carried in
associated ring grooves formed in the outer wall of the piston body
22. The piston body
22 also has a skirt
36 which depends from the piston ring
20 region and helps guide the piston body
22 during reciprocation within the cylinder during operation of the engine. At least
a portion of the skirt
36 is generally cylindrically-shaped and has an outer surface which extends continuously
around a circumference. This portion of the skirt
36 is sized to be close to but relatively smaller than the inner diameter of the cylinder
wall
24 such that there is an operating gap
38 therebetween. The piston body
22 is coupled by a wrist pin (not shown) or a similar type of connection device to a
connecting rod
40, which in turn is coupled to a crank shaft (not shown) or a similar mechanism.
[0010] Referring still to Figures 2 and 3, in its location in the channel
32 of the cylinder wall
24, the exemplary piston ring
20 is mounted stationarily relative to the engine block
28 and is sealed against the outer surface of the skirt
36 of the piston body
22 to establish a gas and fluid tight seal between the cylinder wall
24 and the piston body
22. The piston ring
20 has an inner face
42 (best shown in Figure 4) that is in running contact with the skirt
36 of the piston body
22 during operation of the engine to seal combustion gasses in the combustion chamber
on one side of the piston body
22 and to seal oil on the other side of the piston body
22, e.g. in a crank case (not shown) or any other oil chamber. During operation of the
engine, the piston body
22 moves up and down within the cylinder wall
24 between a top dead center position shown in Figure 2 and a bottom dead center position
shown in Figure 3. As shown, the exemplary piston ring
20 remains in sealing engagement with the circumferentially continuous portion of the
skirt
36 to maintain the gas and oil tight seal throughout the piston body's
22 range of travel. The location of the piston ring
20 in the channel
32 of the cylinder wall
24 allows for increased stability of the piston body
22 as it reciprocates in the cylinder of the engine without compromising the length
of the skirt
36, i.e. the skirt 36 may extend downwardly into the crank case (not shown) when the
piston body
22 is in the bottom dead center position.
[0011] Referring back to Figure 1, the exemplary piston ring
20 includes a ring body
44 that extends about an axis and has ends which are separated from one another by a
ring gap
46. Referring now to Figure 4, the ring body
44 has an inner face
42 with a pair of ridges
48 which are spaced axially from one another and extend in a radially inward direction.
As shown, when installed in a power cylinder assembly
26, these ridges
48 directly and slidably engage the circumferentially continuous portion of the outer
surface of the piston body
22 to establish the gas and oil tight seal between the cylinder wall
24 and the piston body
22. Between the ridges
48, the inner face
42 of the exemplary ring body
44 includes a generally flat valley region
50. In the exemplary embodiment, the top and bottom surfaces of the ridges
48 are angled relative to the radial direction. These surfaces may be disposed at similar
or different angles relative to the radial direction. For example, in the exemplary
embodiment, the surfaces of the ridges
48 nearest the valley region
50 are disposed at approximately a ten degree angle relative to the radial direction,
and the surfaces of the ridges
48 (opposite of the valley region
50) furthest from the valley region
50 are disposed at an angle of approximately twenty degrees relative to the radial direction.
In the exemplary embodiment, the portions of the inner face
42 above and below the ridges
48 are also disposed at an angle relative to the radial direction by approximately eighty
degrees. It should be appreciated that these surfaces could be disposed at any suitable
angles relative to the radial or axial direction and could have any suitable dimensions.
Additionally, in the exemplary embodiment, the intersections of the various surfaces
of the inner face
42 are rounded or radiused. However, it should be appreciated that these intersections
could alternately be sharp, i.e. non-rounded.
[0012] Referring still to Figure 4, the side of the ring body
44 opposite of the inner face
42 is an outer face
52 which presents a generally V-shaped groove
54. The piston ring
20 includes a spring
56 of an elastomeric material which is seated in the groove
54 and substantially circumferentially surrounds the ring body
44. Specifically, the spring
56 is an O-ring of a synthetic rubber, a natural rubber or a thermoplastic material.
The O-ring spring
56 exerts a biasing force against the ring body
44 to bias the ridges
48 of the inner face
42 against the outer surface of the piston body
22 and establish the aforementioned gas and oil tight seal between the cylinder wall
24 and the piston body
22 when installed in the groove
54 of the ring body
44.
[0013] Referring now to Figure 6, the ring body
44 of the exemplary piston ring
20 includes a plurality of oil drainage ports
58 which are generally uniformly spaced from one another in a circumferential direction
along the length of the ring body
44. However, it should be appreciated that the spacing between the oil drainage ports
58 may be varied. Referring back to Figure 4, the oil drainage ports
58 extend at an angle relative to the radially inward direction from the inner face
42 to the outer face
52 on one axial side of the spring
56 for conveying oil out of the space between the ridges
48. Because the oil drainage ports
58 extend at an angle relative to the radially inward direction, they do not interfere
with the inner-most surfaces of the ridges
48 and thus do not compromise the oil and gas seal between the cylinder wall
24 and the piston body
22 provided by the piston ring
20. Additionally, the oil drainage ports
58 do not compromise the structural integrity of the ring body
44. In the exemplary embodiment, each of the oil drainage ports
58 extends from at least a portion of one of the ridges
48 on the inner face
42 to at least a portion of the groove
54 on the outer face
52. The oil that is conveyed from the space between the ridges
48 to the other side of the ring body
44 may then drain back to the crank case or the oil chamber below the piston body
22 during upward strokes of the piston body
22.
[0014] The ring body
44 may be formed through any desirable manufacturing process and may be of any desirable
material including, for example, cast iron or steel. The ring body
44 may also either be uncoated or may have a wear resistant coating (such as chromium,
chromium with aluminum oxide ceramic [CKS], chromium with microdiamond [GDC], etc.)
applied to at least its inner face
42.
[0015] The exemplary description of the embodiment is meant to be illustrative and not limiting
of the invention. Variations and modifications to the disclosed embodiment may become
apparent to those skilled in the art and come within the scope of the claims.
1. A piston ring (20) for sealing a cylinder wall to a piston body (36), comprising:
a ring body (44) extending about an axis and having an inner face (42) and an outer
face (52), said inner face (42) presenting least two ridges (48) that extend in a
radially inward direction with said ridges (48) being spaced axially from one another
by a valley region (50), and said outer face (52) said ridges (48) being spaced axially
from one another by a valley region (50), and said outer face (52) presenting a groove
(54);
a spring (56) of an elastomeric material substantially circumferentially surrounding
said ring body (44) and seated in said groove (54) on said outer face (52), said spring
(56) biasing said ring body (44) in said radially inward direction for sealing said
ridges (48) on said inner face (42) against the piston body (20); and
said ring body (44) having at least one oil drainage (58) port extending at an angle
relative to said radially inward direction from said inner face (42) to a location
on said outer face (52) on one axial side of said spring (56) for conveying oil out
of a space between said ridges (48).
2. The piston ring (20) as set forth in claim 1 wherein said at least one oil drainage
(58) port is further defined as a plurality of oil drainage ports.
3. The piston ring (20) as set forth in claim 2 wherein said plurality of oil drainage
ports are spaced circumferentially from one another.
4. The piston ring (20) as set forth in claim 1 wherein said at least one oil drainage
port extends from a portion of one of said ridges (48) on said inner face (42).
5. The piston ring (20) as set forth in claim 4 wherein said at least one oil drainage
(58) port extends to a portion of said goove (54) on said outer face (52).
6. The piston ring (20) as set forth in claim 1 wherein said at least two radially inwardly
extending ridges (48) on said inner face (42) of said ring body (44) is further defined
as a pair of radially inwardly extending ridges (48).
7. The piston ring (20) as set forth in claim 1 wherein said ring body (44) has a gap
(46).
8. The piston ring (20) as set forth in claim 1 wherein said ring body (44) is uncoated.
9. The piston ring (20) as set forth in claim 1 wherein said ring body (44) is of cast
iron or steel.
10. A power cylinder assembly (26), comprising:
a cylinder wall (24) having a channel (32) formed therein, said channel extending
substantially circumferentially around said cylinder wall (24);
a piston body (22) having a skirt (36) and wherein at least a portion of an outer
surface of said skirt (36) extends substantially continuously around a circumference;
a piston ring (20) disposed in said channel (32) of said cylinder wall;
said piston ring (20) having a ring body (44) that extends about an axis and has an
inner face (42) and an outer face (52), said inner face (42) having at least two ridges
(48) that extend in a radially inward direction, said ridges (48) being spaced axially
from one another by a valley region (50), and said outer face (52) presenting a groove
(54);
said piston ring (20) further including a spring (56) of an elastomeric material substantially
circumferentially surrounding said ring body (44) and seated in said groove (54) on
said outer face (52), said spring (56) biasing said ring body (44) in said radially
inward direction to seal said ridges (48) against said circumferentially continuous
portion of said skirt (36) of said piston body (20); and
said ring body (44) having at least one oil drainage port (58) extending at an angle
relative to said radially inward direction from said inner face (42) to a location
on said outer face (52) on one axial side of said spring (56) for conveying oil out
of a space between said ridges (48).
11. The power cylinder assembly (26) as set forth in claim 10 wherein said at least one
oil oil drainage port (58) is further defined as a plurality of oil drainage ports.
12. The power cylinder assembly (26) as set forth in claim 10 wherein said at least one
oil drainage port (58) extends from at least a portion of one of said ridges (48)
on said inner face (42).
13. The power cylinder assembly (26) as set forth in claim 12 wherein said at least one
oil drainage port (58) extends to said groove (54) on said outer face (52).
14. The power cylinder assembly (26) as set forth in claim 10 wherein said at least two
radially inwardly extending ridges (48) on said inner face (42) of said ring body
(44) is further defined as a pair of radially inwardly extending ridges (48).
15. The power cylinder assembly (26) as set forth in claim 10 wherein said ring body (44)
has a gap (46).
1. Kolbenring (20) zum Abdichten einer Zylinderwand gegen einen Kolbenkörper (36) mit:
einem Ringkörper (44), der sich um eine Achse erstreckt und eine innere Fläche (42)
und eine äußere Fläche (52) aufweist, wobei die innere Fläche (42) zwei Erhöhungen
(48) aufweist, die sich in einer radial nach innen gerichteten Richtung erstreckt,
wobei die Erhöhungen (48) axial voneinander durch einen Vertiefungsbereich (50) getrennt
sind, und wobei die äußere Fläche (52) eine Nut aufweist,
einer Feder (56) aus einem Elastomermaterial, das im Wesentlichen entlang des Umfangs
den Ringkörper (44) umgibt und in der Nut (54) auf der äußeren Fläche (52) sitzt,
wobei die Feder (56) den Ringkörper (44) in der radial nach innen gerichteten Richtung
zum Abdichten der Erhöhungen (48) an der inneren Fläche (42) gegen den Kolbenkörper
(20) vorspannt, und
wobei der Ringkörper (44) wenigstens einen Ölabflussanschluss (58) aufweist, der sich
mit einem Winkel zur radial nach innen gerichteten Richtung von der inneren Fläche
(42) zu einem Ort an der äußeren Fläche (52) an einer axialen Seite der Feder (56)
zum Führen von Öl aus einem Raum zwischen den Erhöhungen (48) erstreckt.
2. Kolbenring (20) nach Anspruch 1, wobei der wenigstens eine Ölabflussanschluss (58)
ferner als mehrere Ölabflussanschlüsse definiert ist.
3. Kolbenring (20) nach Anspruch 2, wobei die mehreren Ölabflussanschlüsse umfänglich
voneinander beabstandet sind.
4. Kolbenring (20) nach Anspruch 1, wobei der wenigstens eine Ölabflussanschluss sich
von einem Abschnitt von einer der Erhöhungen (48) auf der inneren Fläche (42) erstreckt.
5. Kolbenring (20) nach Anspruch 4, wobei der wenigstens eine Ölabflussanschluss (58)
sich zu einem Abschnitt der Nut (54) an der äußeren Fläche (52) erstreckt.
6. Kolbenring (20) nach Anspruch 1, wobei die wenigstens zwei sich radial nach innen
erstreckenden Erhöhungen (48) auf der inneren Fläche (42) des Ringkörpers (44) ferner
als ein Paar sich radial nach innen erstreckender Erhöhungen (48) definiert sind.
7. Kolbenring (20) nach Anspruch 1, wobei der Ringkörper (44) eine Lücke (46) aufweist.
8. Kolbenring (20) nach Anspruch 1, wobei der Ringkörper (44) unbeschichtet ist.
9. Kolbenring (20) nach Anspruch 1, wobei der Ringkörper (44) aus Gusseisen oder Stahl
ist.
10. Arbeitszylinderanordung (26) mit:
einer Zylinderwand (25) mit einem Kanal (32) darin ausgebildet, wobei sich der Kanal
im Wesentlichen umfänglich um die Zylinderwand (24) bewegt,
einem Kolbenkörper (22) mit einem Schaft (36) und wobei wenigstens ein Abschnitt einer
äußeren Oberfläche des Schafts (36) sich im Wesentlichen kontinuierlich um einen Umfang
erstreckt,
einem Kolbenring (20), der in dem Kanal (32) der Zylinderwand vorgesehen ist,
wobei der Kolbenring (20) einen Ringkörper (44) aufwiest, der sich um eine Achse erstreckt
und eine innere Fläche (42) und eine äußere Fläche (52) aufweist, wobei die innere
Fläche (42) wenigstens zwei Erhöhungen (48) hat, die sich in einer radial nach innen
gerichteten Richtung erstrecken, wobei die Erhöhungen (48) axial voneinander durch
einen Talbereich (50) beabstandet sind, und wobei die äußere Fläche (52) eine Nut
(54) aufweist,
wobei der Kolbenring (20) ferner eine Feder (56) aus einem Elastomermaterial aufweist,
welche im Wesentlichen umfänglich den Ringkörper (44) umgibt und welche in der Nut
(54) auf der äußeren Fläche (52) sitzt, wobei die Feder (56) den Ringkörper (44) in
der radial nach innen gerichteten Richtung vorspannt, um die Erhöhungen (48) gegen
den umfänglich kontinuierlichen Abschnitt des Schafts (36) des Kolbenkörpers (20)
abzudichten, und
wobei der Ringkörper (44) wenigstens einen Ölabflussanschluss (38) aufweist, der sich
mit einem Winkel bezüglich der radial nach innen gerichteten Richtung von der inneren
Fläche (42) zu einem Ort an der äußeren Fläche (52) an einer axialen Seite der Feder
(56) erstreckt, um Öl aus einem Raum zwischen den Erhöhungen (48) abzuleiten.
11. Arbeitszylinderanordnung (26) nach Anspruch 10, wobei der wenigstens eine Ölabflussanschluss
(58) ferner als mehrere Ölabflussanschlüsse definiert ist.
12. Arbeitszylinderanordnung (26) nach Anspruch 10, wobei der wenigstens eine Ölabflussanschluss
sich von einem Abschnitt von einer der Erhöhungen (48) auf der inneren Fläche (42)
erstreckt.
13. Arbeitszylinderanordnung (26) nach Anspruch 12, wobei der wenigstens eine Ölabflussanschluss
(58) sich zu einem Abschnitt der Nut (54) an der äußeren Fläche (52) erstreckt.
14. Arbeitszylinderanordnung (26) nach Anspruch 10, wobei die wenigstens zwei sich radial
nach innen erstreckenden Erhöhungen (48) auf der inneren Fläche (42) des Ringkörpers
(44) ferner als ein Paar sich radial nach innen erstreckender Erhöhungen (48) definiert
sind.
15. Arbeitszylinderanordnung (26) nach Anspruch 10, wobei der Ringkörper (44) eine Lücke
(46) aufweist.
1. Segment de piston (20) pour sceller une paroi de cylindre à un corps de piston (36),
comprenant :
un corps de segment (44) s'étendant autour d'un axe et ayant une face intérieure (42)
et une face extérieure (52), ladite face intérieure (42) présentant au moins deux
arêtes (48) qui s'étendent dans une direction radialement vers l'intérieur,
lesdites arêtes (48) étant espacées axialement l'une de l'autre par une région de
vallée (50), et ladite face extérieure (52) présentant une rainure (54) ;
un ressort (56) d'un matériau élastomère entourant sensiblement de manière circonférentielle
ledit corps de segment (44) et installé dans ladite rainure (54) sur ladite face extérieure
(52), ledit ressort (56) poussant ledit corps de segment (44) dans ladite direction
radialement vers l'intérieur pour sceller lesdites arêtes (48) sur ladite face intérieure
(42) contre le corps de piston (20) ; et
ledit corps de segment (44) ayant au moins un orifice d'évacuation d'huile (58) s'étendant
à un certain angle par rapport à ladite direction radialement vers l'intérieur depuis
ladite face intérieure (42) jusqu'à un emplacement sur ladite face extérieure (52)
sur un côté axial dudit ressort (56) pour acheminer de l'huile hors d'un espace entre
lesdites arêtes (48).
2. Segment de piston (20) selon la revendication 1, dans lequel ledit au moins un orifice
d'évacuation d'huile (58) est en outre défini comme une pluralité d'orifices d'évacuation
d'huile.
3. Segment de piston (20) selon la revendication 2, dans lequel ladite pluralité d'orifices
d'évacuation d'huile sont espacés de manière circonférentielle les uns des autres.
4. Segment de piston (20) selon la revendication 1, dans lequel ledit au moins un orifice
d'évacuation d'huile s'étend à partir d'une partie d'une desdites arêtes (48) sur
ladite face intérieure (42).
5. Segment de piston (20) selon la revendication 4, dans lequel ledit au moins un orifice
d'évacuation d'huile (58) s'étend jusqu'à une partie de ladite rainure (54) de ladite
face extérieure (52).
6. Segment de piston (20) selon la revendication 1, dans lequel lesdites au moins deux
arêtes s'étendant radialement vers l'intérieur (48) sur ladite face intérieure (42)
dudit corps de segment (44) sont en outre définies comme une paire d'arêtes s'étendant
radialement vers l'intérieur (48).
7. Segment de piston (20) selon la revendication 1, dans lequel ledit corps de segment
(44) présente un espacement (46).
8. Segment de piston (20) selon la revendication 1, dans lequel ledit corps de segment
(44) est non revêtu.
9. Segment de piston (20) selon la revendication 1, dans lequel ledit corps de segment
(44) est en fonte ou en acier.
10. Ensemble cylindre de puissance (26), comprenant :
une paroi de cylindre (24) ayant un canal (32) formé dans celle-ci, ledit canal s'étendant
sensiblement de manière circonférentielle autour de ladite paroi de cylindre (24)
;
un corps de piston (22) ayant une jupe (36) et dans lequel au moins une partie d'une
surface extérieure de ladite jupe (36) s'étend sensiblement en continu autour d'une
circonférence ;
un segment de piston (20) disposé dans ledit canal (32) de ladite paroi de cylindre
;
ledit segment de piston (20) ayant un corps de segment (44) qui s'étend autour d'un
axe et a une face intérieure (42) et une face extérieure (52), ladite face intérieure
(42) ayant au moins deux arêtes (48) qui s'étendent dans une direction radialement
vers l'intérieur, lesdites arêtes (48) étant espacées axialement l'une de l'autre
par une région de vallée (50), et ladite face extérieure (52) présentant une rainure
(54) ;
ledit segment de piston (20) comprenant en outre un ressort (56) d'un matériau élastomère
entourant sensiblement de manière circonférentielle ledit corps de segment (44) et
installé dans ladite rainure (54) sur ladite face extérieure (52), ledit ressort (56)
poussant ledit segment (44) dans ladite direction radialement vers l'intérieur pour
sceller lesdites arêtes (48) contre ladite partie continue de manière circonférentielle
de ladite jupe (36) dudit corps de piston (20) ; et
ledit corps de segment (44) ayant au moins un orifice d'évacuation d'huile (58) s'étendant
à un certain angle par rapport à ladite direction radialement vers l'intérieur de
ladite face intérieure (42) à un emplacement sur ladite face extérieure (52) sur un
côté axial dudit ressort (56) pour acheminer de l'huile hors d'un espace entre lesdites
arêtes (48).
11. Ensemble cylindre de puissance (26) selon la revendication 10, dans lequel ledit au
moins un orifice d'évacuation d'huile (58) est en outre défini comme une pluralité
d'orifices d'évacuation d'huile.
12. Ensemble cylindre de puissance (26) selon la revendication 10, dans lequel ledit au
moins un orifice d'évacuation d'huile (58) s'étend à partir d'au moins une partie
d'une desdites arêtes (48) sur ladite face intérieure (42).
13. Ensemble cylindre de puissance (26) selon la revendication 12, dans lequel ledit au
moins un orifice d'évacuation d'huile (58) s'étend jusqu'à ladite rainure (54) sur
ladite face extérieure (52).
14. Ensemble cylindre de puissance (26) selon la revendication 10, dans lequel lesdites
au moins deux arêtes s'étendant radialement vers l'intérieur (48) sur ladite face
intérieure (42) dudit corps de segment (44) sont en outre définies comme une paire
d'arêtes s'étendant radialement vers l'intérieur (48).
15. Ensemble cylindre de puissance (26) selon la revendication 10, dans lequel ledit corps
de segment (44) présente un espacement (46).